Field of the Disclosure
Embodiments of the present invention relate to an organic light emitting display device, and more particularly, to a top emission type organic light emitting display device and a method of manufacturing the same.
Discussion of the Related Art
An organic light emitting display (OLED) device, which is a self light emitting display device, has advantages of low power consumption, rapid response speed, high emission efficiency, high luminance, and wide viewing angle.
According to a direction of light emitted from an organic light emitting device, the OLED device may be largely classified into a top emission type and a bottom emission type. In case of the bottom emission type, a circuit device is disposed between an emitting layer and an image displaying surface, whereby an aperture ratio may be lowered due to the circuit device. Meanwhile, in case of the top emission type, a circuit device is not disposed between an emitting layer and an image displaying surface, whereby an aperture ratio may be improved.
FIG. 1 is a cross sectional view of a related art top emission type OLED device.
As shown in FIG. 1, a thin film transistor layer (T) including an active layer 11, a gate insulating film 12, a gate electrode 13, an insulating interlayer 14, a source electrode 15, and a drain electrode 16 is provided on a substrate 10, and then a passivation layer 20 and a planarization layer 30 are sequentially provided on the thin film transistor layer (T).
Also, an anode electrode 40 and an auxiliary electrode 50 are provided on the planarization layer 30. The auxiliary electrode 50 is provided to lower a resistance of a cathode electrode 80 to be explained later.
On the anode electrode 40 and the auxiliary electrode 50, a bank 60 is provided to define a pixel region. Also, an organic emitting layer 70 is provided in the pixel region defined by the bank 60, and the cathode electrode 80 is provided on the organic emitting layer 70.
In case of the top emission type, light emitted from the organic emitting layer 70 passes through the cathode electrode 80. In this reason, the cathode electrode 80 is formed of a transparent conductive material, which causes the increase of resistance therein. In order to lower the resistance in the cathode electrode 80, the cathode electrode 80 is connected with the auxiliary electrode 50.
In order to connect the cathode electrode 80 with the auxiliary electrode 50, an upper surface of the auxiliary electrode 50 is not covered by the organic emitting layer 70. That is, the upper surface of the auxiliary electrode 50 is exposed to the outside after a process of forming the organic emitting layer 70 so that the cathode electrode 80 is connected with the upper surface of the auxiliary electrode 50. In case of the related art, a reverse-tapered partition 65 is provided on the upper surface of the auxiliary electrode 50 so as to prevent the upper surface of the auxiliary electrode 50 from being covered by the organic emitting layer 70.
Owing to the reverse-tapered partition 65, a gap space is provided between the bank 60 and the partition 65. In this case, the reverse-tapered partition 65 serves as an eave so that the organic emitting layer 70 is not deposited in the gap space. That is, the organic emitting layer 70 is formed by a deposition process using a deposition material with superior straightness, for example, evaporation process. According as the partition 65 serves as the eave during the deposition process of the organic emitting layer 70, the organic emitting layer 70 is not deposited in the gap space between the bank 60 and the partition 65.
Meanwhile, the cathode electrode 80 may be formed by a deposition process using a deposition material with inferior straightness, for example, sputtering process. Thus, the cathode electrode 80 may be deposited in the gap space between the bank 60 and the partition 65, whereby the cathode electrode 80 and the auxiliary electrode 50 may be electrically connected with each other.
However, the related art top emission type OLED device inevitably including the reverse-tapered partition 65 may cause the following disadvantages.
A PEB (Post Exposure Bake) process should be carried out so as to pattern the reverse-tapered partition 65. The PEB process is very complicated so that it is difficult to obtain a desired reverse-tapered shape. If the reverse-tapered structure is not formed in a desired shape, the partition 65 may be collapsed or peeled-off. In this case, it is difficult to electrically connect the cathode electrode 80 and the auxiliary electrode 50 with each other.